Dozens of employees at manpower firm NES Group are in line for windfalls as its private equity owner prepares to put the business on the market with a price tag of at least £200m.

Graphite Capital has appointed London-based advisers to sell NES and hopes to complete a deal by the autumn, with another private equity firm the likeliest buyer.

It is understood that just over 100 employees at Altrincham-based NES have shares in the company and could each receive between £10,000 and £100,000, depending on the size of their stake. It is expected that employees and management will reinvest a proportion of their windfalls in the business.

The firm, which supplies technical and engineering staff on permanent and temporary contracts to the oil, gas, power, rail and pharmaceutical sectors, has 31 offices worldwide and a workforce of 400.

Graphite is reigniting the sale process after an unsuccessful attempt to dispose of NES two years ago.

It led a secondary buyout from Bridgepoint Capital in 2006 and has a stake of more than 60 per cent.

The rest of the shares are held by management, led by chief executive Neil Tregarthen, and staff around the globe.

NES, which completed a £105m refinancing last month, has enjoyed stellar growth in recent years, with revenues in the 12 months to October 2011 surging from £278.2m to £380.1m and operating profits up from £12.6m to £16.2m. It was the group's seventh consecutive year of earnings growth.

Its growth so far this year has been even greater, with revenues up 45 per cent.

A source said: “The business is becoming increasingly larger and requires greater investment, hence the decision to sell.

“Graphite will be disappointed if it is not sold for at least £200m, given its strong growth and recent performance.”

NES was established in 1978 by Geoff Lloyd and Bryan Sullivan as Northenden Engineering Services. The duo sold a majority stake to Bridgepoint for about £50m in 1999.